1. Field of the Invention
The invention concerns an ultrasonic microscope including an ultrasonic transmitter by means of which ultrasonic waves can be input-coupled in a sample body, an ultrasonic detector disposed on the opposite side of the sample body from the ultrasonic transmitter and by means of which the ultrasonic waves coupled into the sample body can be detected and which can be positioned relative to the sample body, and a central processor by means of which, as the ultrasonic detector assumes a series of positions relative to the sample body, measurement data assigned to the amplitudes of the input-coupled ultrasonic waves and the amplitudes of the ultrasonic waves detected by the ultrasonic detector can be stored and processed.
2. Description of the Related Art
U.S. Pat. No. 5,675,075 teaches an ultrasonic microscope, including an ultrasonic transmitter by means of which an entire sample body can be irradiated with ultrasonic waves. The prior device also includes an ultrasonic detector which measures with local resolution and which is realized in the form of an atomic force microscope, and by means of which ultrasound-induced deformations occurring on a detecting surface of the sample body can be detected via excursions of a receiving tip of the force microscope. Elasticity properties of the sample body can thus be measured with very high local resolution. The known device has the disadvantage, however, that only measurement values averaged over the region of passage of the ultrasonic waves can be acquired.
The present invention provides an ultrasonic microscope by which data can be acquired even over spatially limited areas in the interior of the sample body.
This task is accomplished by means of an ultrasonic microscope in which ultrasonic waves can be coupled into the sample body by the ultrasonic transmitter in a dotwise or point-sized manner compared to the dimensions of the sample body, in that the ultrasonic transmitter and the ultrasonic detector can be positioned mutually independently on the sample body, and in that a reconstructing unit or image generator is provided by means of which at least one image of internal regions of the sample body can be generated from the ultrasonic amplitudes transmitted by the ultrasonic transmitter at a plurality of transmitting positions and detected by the ultrasonic detector at a plurality of receiving positions with respect to each transmitting positions
The fact that ultrasonic waves can be coupled into the sample body by the ultrasonic transmitter in a point-sized manner and the ultrasonic transmitter and the ultrasonic detector can be positioned independently in relation to each other, the ultrasonic detector being able to detect ultrasonic amplitudes at a plurality of receiving positions for each transmitting position of the ultrasonic transmitter, makes it possible to obtain measurement data by means of which internal regions of the sample body can be imaged sharply by the reconstructing unit, for example on the basis of known tomographic image-generating techniques.
In a preferred embodiment, the ultrasonic detector comprises a force microscope whose resolution is preferably in the atomic range, down to a few tens of nanometers; in a further embodiment, the ultrasonic detector is provided with a tunnel microscope whose resolution is preferably in the atomic range down to a few tens of nanometers.
When a force microscope is used, it is advantageous to provide an optically or capacitively functioning detection unit to detect the excursions of a receiving tip of the force microscope.
In various embodiments, the ultrasonic transmitter is a focusing ultrasonic lens coupled to an ultrasonic transducer, a force microscope coupled to an ultrasonic transducer, or an optical unit comprising an exciting light source, a modulator, and a focusing optic and serving to generate ultrasonic waves on the basis of the thermoelastic effect.
To produce a three-dimensional image of the sample body, it is provided to position the ultrasonic transmitter over the coupling-side surface of the sample body at a plurality of transmitting positions in a grid corresponding to the local resolving power of the ultrasonic transmitter, and, for each transmitting position of the ultrasonic transmitter, to position the ultrasonic detector, also in a grid corresponding to its local resolving power, at a plurality of receiving positions on a detecting surface opposite the coupling-side surface, over a detection-side surface of the sample body in a region where the ultrasound-induced deformation of the detecting surface can be detected. In this manner, data can be acquired from which a complete three-dimensional image of the sample body or images of any desired slices can be reconstructed.
It is also advantageous to provide a sample-body displacing device by means of which the sample body can be displaced in relation to the ultrasonic transmitter to permit irradiation at additional transmitting positions.